06/04/2011

We had a build day for the base of the Solarium today. In the morning I went to the hardware store and bought 23 8' long 2x4's and 5 sheets of plywood. The plywood I had cut at the lumberyard but the 2x4's were cut by Beau, JB and I back at my garage with the mitre saw.

After cutting the wood, JB drilled starter holes for our screws, Beau framed 4 2x4's together to make a rectangle and I nailed the cut plywood to one side of the rectangular frame.

This Thursday Bodhi and I drove down to Menlo Park TechShop to use their 12 ton press to crush the conduit for the Solarium's dome.

One problem we had was getting a flat anvil to put in the machine. Most of the steel anvils available were meant to bend angles into metal, not flatten it. We managed to find a single flat anvil for the top and clamped a peice of scrap steel to the bottom anvil to create two flat surfaces:

The machine is pre-OSHA and we were told to treat it like a loaded gun since it can flatten anything that enters the vice. Its rhythmic motion looks so inoccent though:

With Bodhi's quick use of trigonometry we were able to use a stand to squash the conduit so it flattened the ends at the angle we need for constructing the dome. This saved us about an hour of time later at a vice!

In about 2 hours we finished all 120 peices of conduit, or 240 crushes. With a little bit of grinding at the ends to remove sharp bits, we were done!

05/30/2011

I finally sat down and re-learned all the Google Sketchup that leaked out of my brain and created a model of the wooden base for the Solarium:

Its pretty simple but creating it was challenging enough to make me swear and shake fists. The yellow ended frames are slightly wider than the blue ended frames to match the dome segments they will hold. The first row of struts from the dome are shown in silver sitting on top of the frames.

05/24/2011

05/17/2011

Finished a mapping of all the Beams in the Solarium as they will appear in the dome. The format is similar to a flattened globe with the longitudinal lines showing the curvature. Click through to a full sized vector PDF:

05/06/2011

Its been a long, weird journey, but I think we've found the hydraulic press we need to create the Solarium dome.

Tech Shop was always a likely source for this equipment, but I hadn't been there in years and never to the SF location. The web site didn't indicate they had any kind of press and initial reports from members I know were that nobody has seen one.

I then had a friend confirm that there was definitely a press and other metal working equipment at Tech Shop SF and suggested I contact them directly.

The next day I emailed Zack at Tech Shop SF and got a quick reply that TSSF had a 3-ton manual but not a hydraulic press. For that he said I'd need to visit Tech Shop Menlo where they have a 15-ton hydraulic press.

Great! That weekend I drove down to Menlo Park with Steve C. to check out the press and see what other tools we'd be able to use while there. When we got there however, the staff at the front desk had no knowledge of a hydraulic press. They gave us a tour and showed us a 3-ton manual Arbor press but that's it.

Discouraged (though brimming with ideas from all the other equipment), we returned to the city. I emailed Zach again to let him know what happened and to see if he had any other ideas. His response came back; They have a hydraulic press, its in the Vehicle Bay.

Vehicle Bay!

Apparently the press is "pre-OSHA" which means that it loves to crush fingers, so they only make it available at special request. Zach gave me the name of the facilities guy at Menlo and in a quick email I confirmed its existence.

Come mid-May I am going to crush some conduit! I'll be soliciting anyone with a Tech Shop membership to join me so we can pipeline the following steps of drilling and bending.

05/01/2011

Noise on the power line seems to be the major cause of problems for the Solarium lights. In the last post about getting the lights working without freezing, I actually found that they worked longer but still died after a few hours.

Examining the data sheets a little closer I realized I had neglected to place capacitors near all the chips. Capacitors have many functions, but one important thing they do is absorb noise. A capacitor will block a constant voltage but lets changing voltages pass through. Put a capacitor between the power lead of an IC and ground and the constant 5v power will be delivered to the chip while (most) fluctuations will drop through the capacitor to ground.

Having clean power (read constant and unchanging) is important because the 5v power is a reference for how a digital device determines what's a 1 (5v) and what's a 0. Noisy power can confuse these devices and cause unpredictable behavior. In the Ray's case, the noise is comming from the signals to the LEDs themselves.

I started by putting a capactor across the power inputs of the chip that is supposed to allow longer cable lengths (important since the Rays will be about 6 feet away from each other). After doing this the lights ran for over a day before I stopped them.

Next I added a longer 6.5' cable to test driving a longer length. This introduced a new type of problem; the lights would not freeze but changed more slowly, stuttering and irregular. I examined the power at the end of the cable and found it to be very noisy. Each IC on the Ray has a capacitor next to it, but I had not placed a capacitor across the power line where it connects to the PCB. Adding one cleaned up the power and allowed the lights to run smoothly.

I'd always been told as a general rule to put a capacitor as close as possible to each IC and one where power enterers the board. I understood the reason, but I'd never seen it affect anything in practice (likely because I'd worked in small, ideal conditions). Debugging this was a great illustration of how important this rule is.

04/28/2011

After struggling with the lights a bit, I finally go the lights working continuously:

Previously they would follow their program correctly for anywhere from 30 seconds to several minutes. Inevitably however, the lights would freeze and stop changing. I would then have to power cycle the ray and restart the program.

The answer were a pair of pull-up resistors on the clock and serial lines. These hold each line at +5v or a logic '1' . The devices connected then just have to pull the lines down to 0v to send a signal. The resistor values I had were the recommended values but were actually too high (1oK ohm) for the configuration I was using. Reducing these to 1K ohm did the trick.

04/24/2011

Had a great work weekend for the dome section of the Solarium! On Saturday Janet and I went Discount Builder Supply and bought two 8 foot 2" x 12" planks to serve as a work space and some bolts to hold it down. We bolted down the planks to the saw horses and then bolted down the mitre saw to our new bench. We then created a wooden stop and clamped it at the exact length we needed the conduit cut.

Here's the finished setup:

To help support the long length of the conduit Janet had the stellar idea to use one of the microphone stands I had in the garage:

Sunday morning Janet and Amit showed up to cut the 24 peices of 10' conduit to length. Here's Janet cutting through the conduit:

After that we cleaned up the ends with pliers and a file (to make them safe) and label each length with colored duct tape. Here's the finished product, 120 peices of conduit in three different lengths: